body {
  padding: 0;
  margin: 0;
}
.nav-bar {
  display: flex;
  height: 49px;
  line-height: 49px;
}
.nav-left,
.nav-right {
  width: 70px;
  text-align: center;
  background: red;
}
.nav-center {
  flex: 1;
  background-color: skyblue;
}
